To develop biochemical approaches to the study of the surface membrane components of differentiating neurons which are responsible for vectoral cell migration (chemotaxis) and cell recognition, the cellular slime molds, which exhibit both of these morphogenetic functions, have been chosen as a model system. Species specific cell adhesion appears to be mediated by the high affinity interaction of cell surface carbohydrate binding proteins with complementary cell surface oligosaccharide containing receptors. Following solubilization and affinity purification, structural studies of both these components in the species D. discoideum and P. Pallidum will be undertaken with emphasis on a comparative study of regions of structure responsible for their high affinity interaction, and which interact with the cell membrane. Amino acid sequence determination of the carbohydrate binding proteins will be undertaken. The cAMP receptor of D. discoideum which functions in chemotaxis will be studied with regard to its binding properties and its interactions with other membrane components, such as the cell adhesion apparatus, which appear to have a role in regulating its activity. Affinity labelling methods to be developed, in conjunction with affinity purification techniques, selective fragmentation and peptide isolation will allow correlation of regions of function and membrane association with the linear covalent structures of the carbohydrate binding proteins, their receptors and the cAMP receptor. The sum of these studies will provide an understanding of the role of specific cell membrane macromolecules in the related functions of chemotaxis and specific cell adhesion.